You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
123 lines
3.6 KiB
123 lines
3.6 KiB
//---------------------------------------------------------------------------- |
|
// Anti-Grain Geometry - Version 2.4 |
|
// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com) |
|
// |
|
// Permission to copy, use, modify, sell and distribute this software |
|
// is granted provided this copyright notice appears in all copies. |
|
// This software is provided "as is" without express or implied |
|
// warranty, and with no claim as to its suitability for any purpose. |
|
// |
|
//---------------------------------------------------------------------------- |
|
// Contact: mcseem@antigrain.com |
|
// mcseemagg@yahoo.com |
|
// http://www.antigrain.com |
|
//---------------------------------------------------------------------------- |
|
// |
|
// class ellipse |
|
// |
|
//---------------------------------------------------------------------------- |
|
|
|
#ifndef AGG_ELLIPSE_INCLUDED |
|
#define AGG_ELLIPSE_INCLUDED |
|
|
|
#include "agg_basics.h" |
|
#include <cmath> |
|
|
|
namespace agg |
|
{ |
|
|
|
//----------------------------------------------------------------ellipse |
|
class ellipse |
|
{ |
|
public: |
|
ellipse() : |
|
m_x(0.0), m_y(0.0), m_rx(1.0), m_ry(1.0), m_scale(1.0), |
|
m_num(4), m_step(0), m_cw(false) {} |
|
|
|
ellipse(double x, double y, double rx, double ry, |
|
unsigned num_steps=0, bool cw=false) : |
|
m_x(x), m_y(y), m_rx(rx), m_ry(ry), m_scale(1.0), |
|
m_num(num_steps), m_step(0), m_cw(cw) |
|
{ |
|
if(m_num == 0) calc_num_steps(); |
|
} |
|
|
|
void init(double x, double y, double rx, double ry, |
|
unsigned num_steps=0, bool cw=false); |
|
|
|
void approximation_scale(double scale); |
|
void rewind(unsigned path_id); |
|
unsigned vertex(double* x, double* y); |
|
|
|
private: |
|
void calc_num_steps(); |
|
|
|
double m_x; |
|
double m_y; |
|
double m_rx; |
|
double m_ry; |
|
double m_scale; |
|
unsigned m_num; |
|
unsigned m_step; |
|
bool m_cw; |
|
}; |
|
|
|
//------------------------------------------------------------------------ |
|
inline void ellipse::init(double x, double y, double rx, double ry, |
|
unsigned num_steps, bool cw) |
|
{ |
|
m_x = x; |
|
m_y = y; |
|
m_rx = rx; |
|
m_ry = ry; |
|
m_num = num_steps; |
|
m_step = 0; |
|
m_cw = cw; |
|
if(m_num == 0) calc_num_steps(); |
|
} |
|
|
|
//------------------------------------------------------------------------ |
|
inline void ellipse::approximation_scale(double scale) |
|
{ |
|
m_scale = scale; |
|
calc_num_steps(); |
|
} |
|
|
|
//------------------------------------------------------------------------ |
|
inline void ellipse::calc_num_steps() |
|
{ |
|
double ra = (std::fabs(m_rx) + std::fabs(m_ry)) / 2; |
|
double da = std::acos(ra / (ra + 0.125 / m_scale)) * 2; |
|
m_num = uround(2*pi / da); |
|
} |
|
|
|
//------------------------------------------------------------------------ |
|
inline void ellipse::rewind(unsigned) |
|
{ |
|
m_step = 0; |
|
} |
|
|
|
//------------------------------------------------------------------------ |
|
inline unsigned ellipse::vertex(double* x, double* y) |
|
{ |
|
if(m_step == m_num) |
|
{ |
|
++m_step; |
|
return path_cmd_end_poly | path_flags_close | path_flags_ccw; |
|
} |
|
if(m_step > m_num) return path_cmd_stop; |
|
double angle = double(m_step) / double(m_num) * 2.0 * pi; |
|
if(m_cw) angle = 2.0 * pi - angle; |
|
*x = m_x + std::cos(angle) * m_rx; |
|
*y = m_y + std::sin(angle) * m_ry; |
|
m_step++; |
|
return ((m_step == 1) ? path_cmd_move_to : path_cmd_line_to); |
|
} |
|
|
|
} |
|
|
|
|
|
|
|
#endif |
|
|
|
|
|
|